Informing and Advancing Effective Policy

Some Schools Much Better Than Others at Closing Achievement Gaps Between Their Advantaged and Disadvantaged Students

Important new work by Reardon and his collaborators shows that not only test scores but also racial test score gaps vary dramatically across American school districts. In this latter paper, Reardon and coauthors report that while racial/ethnic test score gaps average around 0.6 standard deviations across all school districts, in some districts the gaps are almost nonexistent while in others they exceed 1.2 standard deviations. There are many potential explanations for this cross-district variation in achievement gaps, including racial differences in socioeconomic status , differences in racial/ethnic segregation, differences in school and neighborhood quality, and the like; and the evidence to date about what the leading causes of this variation are is descriptive, rather than causal. Nonetheless, the fact remains that in some places, racial/ethnic and socioeconomic differences are extraordinarily larger than in other places. These differences also correlate with important long-run economic outcomes as documented in a new work by Chetty and co-authors, where they find suggestive evidence that “quality of schools—as judged by outputs rather than inputs—plays a role in upward mobility.”

CEPA Publications

In this chapter I examine whether and how the relationship between family socioeconomic characteristics and academic achievement has changed during the last fifty years. In particular, I investigate the extent to which the rising income inequality of the last four decades has been paralleled by a similar increase in the income achievement gradient. As the income gap between high- and low-income families has widened, has the achievement gap between children in high- and low-income families also widened?

The answer, in brief, is yes. The achievement gap between children from high- and low-income families is roughly 30 to 40 percent larger among children born in 2001 than among those born twenty-five years earlier. In fact, it appears that the income achievement gap has been growing for at least fifty years, though the data are less certain for cohorts of children born before 1970. In this chapter, I describe and discuss these trends in some detail. In addition to the key finding that the income achievement gap appears to have widened substantially, there are a number of other important findings.

First, the income achievement gap (defined here as the average achievement difference between a child from a family at the 90th percentile of the family income distribution and a child from a family at the 10th percentile) is now nearly twice as large as the black-white achievement gap. Fifty years ago, in contrast, the black-white gap was one and a half to two times as large as the income gap. Second, as Greg Duncan and Katherine Magnuson note in chapter 3 of this volume, the income achievement gap is large when children enter kindergarten and does not appear to grow (or narrow) appreciably as children progress through school. Third, although rising income inequality may play a role in the growing income achievement gap, it does not appear to be the dominant factor. The gap appears to have grown at least partly because of an increase in the association between family income and children's academic achievement for families above the median income level: a given difference in family incomes now corresponds to a 30 to 60 percent larger difference in achievement than it did for children born in the 1970s. Moreover, evidence from other studies suggests that this may be in part a result of increasing parental investment in children's cognitive development. Finally, the growing income achievement gap does not appear to be a result of a growing achievement gap between children with highly and less-educated parents. Indeed, the relationship between parental education and children's achievement has remained relatively stable during the last fifty years, whereas the relationship between income and achievement has grown sharply. Family income is now nearly as strong as parental education in predicting children's achievement.

This paper provides the first population-based evidence on how much standardized test scores vary among public school districts within each state and what factors explain that variation. Using over 200 million standardized test records in math and ELA for grades 3 through 8 from every U.S. public school district during the 2008-09 to 2012-13 school years, we estimate intraclass correlations (ICCs) as a measure of between-district variation. We characterize the variation in the ICCs across states, as well as the patterns in the ICCs over subjects, grades and cohorts. Further, we investigate the relationship between the ICCs and measures of racial and socioeconomic segregation. We find that between-district variation is greatest, on average, in states with high levels of both white-black and economic segregation among school districts.

We estimate racial/ethnic achievement gaps in several hundred metropolitan areas and several thousand school districts in the United States using the results of roughly 200 million standardized math and reading tests administered to public school students from 2009-2013. We show that achievement gaps vary substantially, ranging from nearly 0 in some places to larger than 1.2 standard deviations in others. Economic, demographic, segregation and schooling characteristics explain roughly three-quarters of the geographic variation in these gaps. The strongest correlates of achievement gaps are local racial/ethnic differences in parental income, local average parental education levels, and patterns of racial/ethnic segregation, consistent with a theoretical model in which family socioeconomic factors affect educational opportunity partly though residential and school segregation patterns.